The present disclosure relates to a sheet size setting device for indicating the size of sheets stored in a sheet cassette and having a sheet feeder or an image forming apparatus including the sheet cassette automatically recognize the sheet size.
An image forming apparatus such as a printer, a copier, a facsimile machine or a complex machine of these includes a sheet cassette for storing a plurality of sheets to which an image forming process is to be applied. Normally, a plurality of sheet cassettes storing different sizes of sheets are removably mounted in an apparatus main body of an image forming apparatus. Here, it is desirable to indicate which size of sheets are stored in which sheet cassette to a user and have the apparatus main body automatically recognize the sheet sizes. The present assignee has previously proposed a sheet size setting device which realizes both of these functions.
The conventionally proposed sheet size setting device is a dial-type sheet size setting device including a sheet size indicator and a detection pattern unit identifiable by a predetermined detection sensor for each size indicated on the indicator. A user turns the sheet size setting device to a proper position according to the size of sheets stored in the sheet cassette, whereby the sheet size is indicated by the indicator and identified by the detection sensor.
Sheets to be stored in the sheet cassettes include sheets of standard sizes such as “B5”, “A4”, “B4” and “A3” and uniquely-sized sheets (hereinafter, referred to as “Other sheets”). In the conventional sheet size setting device, a switch between sheets of standard sizes and Other sheets can be made by a simple dial changing operation. Thus, even if the sheet size is set at “Other sheets”, the set sheet size may be easily changed by an erroneous operation.
Normally, a sheet cassette includes a sensor function of detecting the size of sheets accommodated therein for sheets of standardized sizes. Accordingly, even if the size is erroneously set among sheets of standardized sizes, such an error can be easily corrected. However, in the case of Other sheets, the sensor function is invalidated and the sheet size input by the user through an operation panel or the like is set. Thus, if the sheet size is erroneously set between Other sheets and sheets of standardized sizes, it takes time and effort for a correction.
An object of the present disclosure is to provide a sheet size setting device capable of maximally suppressing erroneous setting of a sheet size while easily setting the sheet size, and a sheet feeder or an image forming apparatus to which the sheet size setting device is applied.